Q. Do amphibians have direct development?

In amphibians the embryonic development is indirect there is a larval stage.

Q. How different are the respiration in adult amphibians and the respiration in fishes?

In fishes gas exchange is done by direct contact of water with the branchiae (gills), Exit the circulation through the gills and Gases gain.

In adult amphibians gas exchange is done through permeable skin (cutaneous respiration) and the moist  and also through the lungs a set of tiny airway terminations associated to a highly vascularized tissue specialized in gas exchange, the axolotl is an exotic amphibian found in Mexico that lives in water and "breathes" through gills even as an adult.